Lowering the age for communion is better in all ways possible, but mainly because it makes the recipient living a Holy Life in communion with God from an earlier age. And they also make the preparations for their first communion from an earlier age.
In the well known apparition of a Lost Soul from Hell, this is said about the fact of the Pope lowering the age of communion:
- The condemned soul speaking of her own communion, contrasting it with the lower age permitted afterwards: "The important thing is that we were not allowed to receive Communion until the age of 12. By then I was already absorbed in worldly amusements and found it easy to set aside, without scruple, the things of religion. Thus, I attached no great importance to my first Communion. We are furious that many children go to Communion at the age of seven. We do all we can to make people believe that children have insufficient knowledge at that age. They must first commit some mortal sins. Then the white Particle will not do so much damage to our cause as when faith, hope, and charity - oh, these things! - received in Baptism, are still alive in their hearts."
https://www.olrl.org/doctrine/cry.shtml
Nice to have someone respond to my comment!
As regards receiving communion at the age of seven, I don't imagine Pope St. Pius X foresaw that a time would come -- the time has been with us for quite a while now -- when the Sacrament of Holy Eucharist would be given to children on a wide scale basis before their receipt of the Sacrament of Penance. What a diabolical deceit this has been, no doubt with grave diabolical implications and results as regards desensitizing children from an early age to sin. Before the child was taught to purify his heart and soul by the Sacrament of Penance before his first Holy Communion. Alas, no more!